1. Field of the Invention
This invention relates to a body fluid sampling device for analyzing and quantifying the ingredients contained in body fluid such as blood, lymph and intercellular liquid. More specifically, the present invention relates to a body fluid sampling device that is highly advantageous to the subject when the subject samples body fluid by him- or herself because of simplicity and correctness and the low risk of intrusion and admixture of impurities.
2. Description of the Related Art
The importance of health examinations including medical checkups has been increasing in recent years due to the rising tide of the social concern to the health and the increase in the number of patients of lifestyle related diseases that are attributable to changes in the diet and the lifestyle. On the other hand, there is a tendency of trying to grasp the health condition of each individual by him- or herself because of the high cost of medical treatments in our aging society with fewer children. Actually, so-called mail health examination systems of sampling own blood and sending it to a relevant examination facility by mail have already started to operate for biochemical examinations such as liver function tests and immunity examinations for infectious diseases and tumor markers to say nothing of measurement of the blood sugar level.
Furthermore, devices adapted to examine the body fluid sampled by the subject on site have been developed by exploiting microprocessing technologies and micro-fluid control technologies. As for such micro-devices for physical examinations, the techniques relating to body fluid and sampled body fluid specimens as listed below have been disclosed to date.
Japanese Patent Application Laid-Open No. 2002-263085 discloses a method of sampling blood by a small quantity by means of which it is possible to complete the sequence of a blood sampling process simply by pushing a small sampling mechanism against the skin surface of the sampling site typically by a fingertip. Japanese Patent Application Laid-Open No. 2003-083958 discloses a method of sampling blood by enclosing the outer periphery of a syringe by means of a cylinder in order to keep the inside airtight and produce negative pressure there so as to suck in the skin and make it protrude and then driving the syringe needle to needle the skin. The Patent Document describes that the syringe can be positioned and anchored reliably by such a needling method. Japanese Patent Application Laid-Open No. 2000-185034 discloses a blood sampling/analyzing device comprising a very small blood sampling needle formed by molding silicone with a hollow internal section disposed in the needle body, a pump section and an analyzing section arranged on a single substrate.
All the above-listed known blood fluid sampling devices are devised in such a way that the liquid conveying element, the analyzing element and the needling means such as a sampling needle are interlocked so that the sampled body fluid such as blood may not be exposed to the outside and only a small quantity of body fluid is sufficient for the analysis. However, such devices basically require an arrangement for bringing the needling means close to the surface of the skin or the mucous membrane of a living body, needling the skin or the mucous membrane and sucking the body fluid taken out from the body after the needling by means of a special mechanism arranged at the device side. Such an arrangement more often than not makes the device a complex one. Thus, it may be very useful to provide a body fluid sampling device that can meet the following performance requirements.
(1) The psychological barrier against needling is reduced and the subject can positively and autonomously control the pain produced by the needling.
(2) The body fluid taken out from the body by the needling means can be conveyed into the device without using a special sucking means or sucking mechanism.